Global warming caused by the emission of a greenhouse effect gas is a global problem. As examples of the greenhouse effect gases, carbon dioxide (CO2), methane (CH4), and fluorocarbons (CFCs) are known. Among those gases, CO2 has the greatest impact and the establishment of a system for separating and removing CO2 from a thermal electric power plant, a steel plant, and the like has been an urgent issue.
Further, CO2 also has an affect on the human body. For example, when a gas containing CO2 of a high concentration is inhaled, a health hazard is caused and hence the control of a CO2 concentration is required in an enclosed space such as a room interior. In particular, a device for removing CO2 is required in an environment where outdoor air and indoor air are hardly interchangeable such as a space station. In other fields too, a system for removing CO2 is required because CO2 possibly has a negative effect during the manufacture of foods and chemical products.
Known examples of methods for solving the problem are a chemical absorption method, a physical absorption method, a membrane separation method, an adsorptive separation method, and a cryogenic distillation method. Among those methods, there is a CO2 separation and recovery method using a solid CO2 capturing material. In a CO2 removal system using a CO2 capturing material, CO2 is captured by introducing a CO2 containing gas into a capturing material container filled with the CO2 capturing material and bringing the CO2 containing gas into contact with the CO2 capturing material at the atmospheric pressure or an added pressure under a prescribed temperature condition. Successively, the captured CO2 is desorbed by heating the capturing material or depressurizing the interior of the capturing material container. The CO2 capturing material from which CO2 is desorbed is cooled or depressurized and the solid CO2 capturing material is initialized. The CO2 capturing material is used for removing CO2 from a CO2 containing gas by repeating capture and desorption as stated above. Further, it can be used also for separating and recovering CO2 at a high concentration from a CO2 containing gas by the above mechanism.
In such a device for capturing and removing CO2, zeolite is mainly used as a CO2 capturing material. For example, Patent Literature 1 describes a CO2 removal method of adsorbing CO2 by bringing a gas containing CO2 into contact with a CO2 adsorptive agent of a zeolite type and successively desorbing CO2 by heating it.